// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "chrome/browser/extensions/api/mdns/dns_sd_registry.h"

#include "base/stl_util.h"
#include "chrome/browser/extensions/api/mdns/dns_sd_device_lister.h"
#include "chrome/browser/local_discovery/service_discovery_shared_client.h"

using local_discovery::ServiceDiscoveryClient;
using local_discovery::ServiceDiscoverySharedClient;

namespace extensions {

namespace {
// Predicate to test if two discovered services have the same service_name.
class IsSameServiceName {
 public:
  explicit IsSameServiceName(const DnsSdService& service) : service_(service) {}
  bool operator()(const DnsSdService& other) const {
    return service_.service_name == other.service_name;
  }

 private:
  const DnsSdService& service_;
};
}  // namespace

DnsSdRegistry::ServiceTypeData::ServiceTypeData(
    scoped_ptr<DnsSdDeviceLister> lister)
    : ref_count(1), lister_(lister.Pass()) {}

DnsSdRegistry::ServiceTypeData::~ServiceTypeData() {}

void DnsSdRegistry::ServiceTypeData::ListenerAdded() {
  ref_count++;
}

bool DnsSdRegistry::ServiceTypeData::ListenerRemoved() {
  return --ref_count == 0;
}

int DnsSdRegistry::ServiceTypeData::GetListenerCount() {
  return ref_count;
}

bool DnsSdRegistry::ServiceTypeData::UpdateService(
      bool added, const DnsSdService& service) {
  DnsSdRegistry::DnsSdServiceList::iterator it =
      std::find_if(service_list_.begin(),
                   service_list_.end(),
                   IsSameServiceName(service));
  // Set to true when a service is updated in or added to the registry.
  bool updated_or_added = added;
  bool known = (it != service_list_.end());
  if (known) {
    // If added == true, but we still found the service in our cache, then just
    // update the existing entry, but this should not happen!
    DCHECK(!added);
    if (*it != service) {
      *it = service;
      updated_or_added = true;
    }
  } else if (added) {
    service_list_.push_back(service);
  }

  VLOG(1) << "UpdateService: " << service.service_name
          << ", added: " << added
          << ", known: " << known
          << ", updated or added: " << updated_or_added;
  return updated_or_added;
}

bool DnsSdRegistry::ServiceTypeData::RemoveService(
    const std::string& service_name) {
  for (DnsSdRegistry::DnsSdServiceList::iterator it = service_list_.begin();
       it != service_list_.end(); ++it) {
    if ((*it).service_name == service_name) {
      service_list_.erase(it);
      return true;
    }
  }
  return false;
}

bool DnsSdRegistry::ServiceTypeData::ClearServices() {
  lister_->Discover(false);

  if (service_list_.empty())
    return false;

  service_list_.clear();
  return true;
}

const DnsSdRegistry::DnsSdServiceList&
DnsSdRegistry::ServiceTypeData::GetServiceList() {
  return service_list_;
}

DnsSdRegistry::DnsSdRegistry() {
#if defined(ENABLE_SERVICE_DISCOVERY)
  service_discovery_client_ = ServiceDiscoverySharedClient::GetInstance();
#endif
}

DnsSdRegistry::DnsSdRegistry(ServiceDiscoverySharedClient* client) {
  service_discovery_client_ = client;
}

DnsSdRegistry::~DnsSdRegistry() {}

void DnsSdRegistry::AddObserver(DnsSdObserver* observer) {
  observers_.AddObserver(observer);
}

void DnsSdRegistry::RemoveObserver(DnsSdObserver* observer) {
  observers_.RemoveObserver(observer);
}

DnsSdDeviceLister* DnsSdRegistry::CreateDnsSdDeviceLister(
    DnsSdDelegate* delegate,
    const std::string& service_type,
    local_discovery::ServiceDiscoverySharedClient* discovery_client) {
  return new DnsSdDeviceLister(discovery_client, delegate, service_type);
}

void DnsSdRegistry::RegisterDnsSdListener(std::string service_type) {
  VLOG(1) << "RegisterDnsSdListener: " << service_type
          << ", registered: " << IsRegistered(service_type);
  if (service_type.empty())
    return;

  if (IsRegistered(service_type)) {
    service_data_map_[service_type]->ListenerAdded();
    DispatchApiEvent(service_type);
    return;
  }

  scoped_ptr<DnsSdDeviceLister> dns_sd_device_lister(CreateDnsSdDeviceLister(
      this, service_type, service_discovery_client_.get()));
  dns_sd_device_lister->Discover(false);
  linked_ptr<ServiceTypeData> service_type_data(
      new ServiceTypeData(dns_sd_device_lister.Pass()));
  service_data_map_[service_type] = service_type_data;
  DispatchApiEvent(service_type);
}

void DnsSdRegistry::UnregisterDnsSdListener(std::string service_type) {
  VLOG(1) << "UnregisterDnsSdListener: " << service_type;
  DnsSdRegistry::DnsSdServiceTypeDataMap::iterator it =
      service_data_map_.find(service_type);
  if (it == service_data_map_.end())
    return;

  if (service_data_map_[service_type]->ListenerRemoved())
    service_data_map_.erase(it);
}

void DnsSdRegistry::ServiceChanged(const std::string& service_type,
                                   bool added,
                                   const DnsSdService& service) {
  VLOG(1) << "ServiceChanged: service_type: " << service_type
          << ", known: " << IsRegistered(service_type)
          << ", service: " << service.service_name
          << ", added: " << added;
  if (!IsRegistered(service_type)) {
    return;
  }

  bool is_updated =
      service_data_map_[service_type]->UpdateService(added, service);
  VLOG(1) << "ServiceChanged: is_updated: " << is_updated;

  if (is_updated) {
    DispatchApiEvent(service_type);
  }
}

void DnsSdRegistry::ServiceRemoved(const std::string& service_type,
                                   const std::string& service_name) {
  VLOG(1) << "ServiceRemoved: service_type: " << service_type
          << ", known: " << IsRegistered(service_type)
          << ", service: " << service_name;
  if (!IsRegistered(service_type)) {
    return;
  }

  bool is_removed =
      service_data_map_[service_type]->RemoveService(service_name);
  VLOG(1) << "ServiceRemoved: is_removed: " << is_removed;

  if (is_removed)
    DispatchApiEvent(service_type);
}

void DnsSdRegistry::ServicesFlushed(const std::string& service_type) {
  VLOG(1) << "ServicesFlushed: service_type: " << service_type
          << ", known: " << IsRegistered(service_type);
  if (!IsRegistered(service_type)) {
    return;
  }

  bool is_cleared = service_data_map_[service_type]->ClearServices();
  VLOG(1) << "ServicesFlushed: is_cleared: " << is_cleared;

  if (is_cleared)
    DispatchApiEvent(service_type);
}

void DnsSdRegistry::DispatchApiEvent(const std::string& service_type) {
  // TODO(justinlin): Make this MaybeDispatchApiEvent instead and dispatch if a
  // dirty bit is set.
  VLOG(1) << "DispatchApiEvent: service_type: " << service_type;
  FOR_EACH_OBSERVER(DnsSdObserver, observers_, OnDnsSdEvent(
      service_type, service_data_map_[service_type]->GetServiceList()));
}

bool DnsSdRegistry::IsRegistered(const std::string& service_type) {
  return service_data_map_.find(service_type) != service_data_map_.end();
}

}  // namespace extensions